Where to recharge A/C

[jsbihn]

Hey all,
Just trying to figure out the right valve to recharge my A/C unit.

http://i639.photobucket.com/albums/uu112/esheri/HUMMER%20H2/IMG_0168.jpg

I know it is one of these two (black capped shreader valves), but which one?
By the looks, it seems like it shouldnt matter but I want to make sure before I waste 50 bucks in freon.

Thanks

[jsbihn]

I actually figured it out
Thank you though